For many viewers of "Jon & Kate Plus 8," the attraction is watching not just two sets of multiples -- 7-year-old fraternal twin girls and 4-year-old sextuplets -- but also their parents' unvarnished marriage.

The weekly series, now in its fourth season, focuses on the lives of a central Pennsylvania family. Jon Gosselin, 31, a systems engineer, and his wife Kate, 33, a former nurse, are the parents of twins Mady and Cara and sextuplets Aaden, Alexis, Collin, Hannah, Joel and Leah.

Every week viewers observe the couple working through the logistical, financial and emotional problems inherent in caring for their unexpectedly large brood, which is the result of fertility treatments.

Like real-life couples, the Gosselins can be snarky and impatient with each other, although they summon impressive reserves of patience and understanding when dealing with their children. "I'm not always proud of what you see on the show, nor is Jon," Kate Gosselin said, but "we're certainly not going to hide our imperfections."

Jon, a master of facial expressions, at times rolls his eyes; he tells his wife, who's averse to anything remotely messy, to "stop flipping out" when their kids get dirty. Kate, displeased by how little she thinks her husband is doing, asks acerbically, "Can we have a 'Kate and Jon Switch' day where I get to stand around and cross my arms?"

But for someone with eight children age 7 or younger, Kate is usually remarkably calm -- not to mention remarkably organized.

Executive producer Wendy Douglas said she believes the couple's periodic sniping is one reason for the show's popularity.

"They don't yell and scream at each other, but many people appreciate it because it's so real. And it's a testament to Jon and Kate that they allow us to shoot all of it," Douglas said.

"I'm actually shocked by the thousands of e-mails that we get from viewers who say that Jon and I" are just like them, Kate Gosselin said in a recent telephone interview, which she interrupted with an emphatic warning to her children "to stop doing that now, please."

Other viewers, she noted, are less sympathetic and write that they are appalled by the couple's bickering.

Gosselin said she told the show's producers she wasn't interested in "painting little pictures and putting a pretty bow on it" -- a fault she found with many media accounts of the sextuplets' 2004 delivery and their first chaotic months at home.

"The goal is to show the world that this job is hard -- a lot harder than Jon and I ever imagined," Gosselin said.